Many schemes based on multiple antennas have been studied to improve link quality between a transmitter and a receiver and support a high data transmission rate in accordance with requirements of a next generation wireless access system. Schemes such as space frequency block coding (SFBC), spatial multiplexing (SM), closed-loop MIMO (CL-MIMO)/beamforming and zero-forcing beamforming (ZFBF) have been applied to LTE or LTE-A system.
Generally, a mobile communication system considers that more antennas are installed in a base station than a user equipment for a reason of physical space and power supply, and the current LTE-A system (release-10) supports maximum 8 Tx system. Among methods for improving link quality by using multiple antennas, in case that channel state information may be used by a transmitter, a beamforming scheme may provide the most excellent throughput. The beamforming scheme may obtain gain for reducing a transmission power or more improved link quality if the number of transmitting antennas is increased. Also, as the number of antennas is increased, beam may be formed sharply and at the same time more orthogonal beams may be generated. In other words, the number of receivers, which may receive their respective data at the same time, is increased. In this respect, a system, which supports large scaled antennas more than the existing 8 Tx antennas, that is, massive MIMO system is considered.